Synthetic rubber compositions are widely used in industry. To achieve a degree of standardization in such materials and products, the International Institute of Synthetic Rubber Producers assigns numbers to various commercial grades of styrene-butadiene rubber (SBR), butadiene polymers, etc. The numbering system instituted under the government synthetic rubber program is still used by private industry, although ASTM code numbers and manufacturers' codes or trade names are also used, particularly for newer products. Producers generally prefix an Institute Code number with their distinguishing trade names.
Manufacturers of rubber articles and products have developed standardized production processes and specifications for the basic rubber materials to be used in such processes. The producers of commercial grade rubbers have developed their markets by providing materials which meet the specifications and requirements of these manufacturers. The production of SBR is now generally directed to grades designed for specific uses. One improvement in SBR compounding for specific end uses has been the preparation of carbon black and/or oil-extended masterbatches of regular and oil-extended cold SBR. Because of the large markets available, it is important that producers provide rubber compositions which uniformly meet commercial specifications. For example, additives effective as accelerators and retarders can be used to adjust the curing time of rubbers to commercial specifications.
For example, U.S. Pat. No. 2,734,039 discloses and claims a process for accelerating the curing of butyl rubber by the addition of zinc compounds and chlorosulfonated polythene to accelerate the reaction of dimethylol phenol (a phenol-formaldehyde resin) with the butyl rubber. The Blue Book 1981, published by Rubber World magazine, discloses at pages 69/70 various retarders for retarding cure and scorch time of rubbers.